BTN seems to be a bit loose/aggressive preflop but a bit passive postflop (based on the limited sample we have).

This tells us that we will have to play a few hands OOP versus them. While Q9s is not that bad it may be hard to play versus a fish that has position on us. So I would recommend considering a fold.

As played the flop cbet is fine however I feel that the turn double barell is a bit light because the K increases our perceived ranged and thus increase our FE versus the weaker part of his range that we want to keep in.

Against someone like him I would instead opt to check and fold if he bets and if he checks back we have the option to throw in a small value bet on the river vs 9x/8x hands.